Canterbury DHB

Anti-Phospholipid Syndrome (APS)

Antibodies with specificity for phospholipids are associated with a predisposition to thrombosis in particular patient populations. To detect antiphospholipid antibodies, two assay techniques are required.

Anticardiolipin antibodies (ACA) are detected by an ELISA method using cardiolipin and the essential cofactor, beta-2 glycoprotein. However, coagulation studies using thromboplastin (SCT or DRVVT) are used to detect lupus anti-coagulant (LAC). It is important to recognise that prolongation of coagulation times are not always due to antiphospholipid antibodies. Anticardiolipin antibodies and the antibodies causing the lupus anticoagulant are different antiphospholipid antibodies that may or may not both be present in the same patient.

While the association of antiphospholipid antibodies and thrombosis is strong, particularly in patients suffering from systemic lupus erythematosis, the predictive value of these antibodies is less well defined. There is general consensus that individuals with a history of recurrent thrombosis or foetal loss who are antibody positive are at great risk of a further thrombotic event. They should be considered (as should cancer) as a cause of recurrent thrombosis despite standard dose warfarin.

The predictive value of antiphospholipid antibodies with respect to thrombosis in otherwise healthy individuals is more difficult to define. The guidelines presented here are an attempt to develop a consensus document after consideration of available data.

Cardinal Features

Clinical features include:

• Venous and/or arterial thrombosis
• One or more unexplained first or midtrimester abortions
• One or more premature births (<34 weeks) due to pre-eclampsia or placental insufficiency

Laboratory criteria:

• Anticardiolipin antibody (ACL) positive in moderate to high titre (greater than 40 units) (IgG and/or IgM antibodies on two occasions > six weeks apart), and / or
• Lupus anti-coagulant (LAC) test positive on 2 occasions > six weeks apart. (LAC = prolonged phospholipid dependant clotting test not corrected by normal plasma, no evidence of FVIII antibodies or heparin). The prolonged clotting time should be shortened or corrected by excess phospholipid.

Other features may be:

• Thrombocytopenia
• Amaurosis fugax
• Migraine
• Chorea
• Marantic heart valve disease, Liebmanns-Sachs endocarditis, culture negative endocarditis
• Coombs positive haemolytic anaemia
• Livedo reticularis
• Purpura fulminans
• Transverse myelitis
• Adrenal infarction
• Budd Chiari syndrome

Note: Antiphospholipid antibodies may be associated with infections such as HIV, syphilis, malaria, and lymphomas and the use of phenothiazines, procainamide, phenytoin, quinidine and hydralazine.

Topic Code: 5203